The shrimp, native to the Pacific Ocean, may have arrived either from aquaculture operations, via ocean currents or in ballast water from ships. They grow and spawn swiftly, putting them in a position to crowd out native shrimp.

“We can confirm there was nearly a tenfold jump in reports of Asian tiger shrimp in 2011,” said Pam Fuller, the USGS biologist who runs the agency’s Nonindigenous Aquatic Species database. “And they are probably even more prevalent than reports suggest, because the more fisherman and other locals become accustomed to seeing them, the less likely they are to report them."

Sightings should be reported at http://nas.er.usgs.gov/SightingReport.aspx.